Bell box strobe not working?

I have a Securit 800L control panel and I have noticed that the strobe light is not working when the system goes into alarm. Is this a faulty strobe which needs replacing and can it be replaced or do I need to change the whole bell box? Also is it possible that it is a damaged cable between the strobe and the alarm panel that has caused the fault (I stood on the wire when i was in the loft)?